The subject matter described and/or illustrated herein relates generally to light emitting diodes (LEDs), and more particularly, to temperature measurement systems for LEDs.
LEDs are being used to replace other lighting systems that use other types of light sources, such as incandescent or fluorescent lamps. LEDs offer advantages over lamps, for example rapid turn-on, rapid cycling (on-off-on) times, long useful life span, low power consumption, narrow emitted light bandwidths that eliminate the need for color filters to provide desired colors, and so on. LEDs are among the longest lasting light sources now available, for example with a useful life span measured in tens of thousands of hours. But, LEDs do experience a gradual reduction in light output over a life span, which is commonly referred to as “light output degradation.” Light output degradation may result from a reduction in the light emitting efficiency of the LED and/or from a reduction in the light transmission of the optical path within an LED.
Relatively high operating temperatures may adversely affect the performance of LEDs. For example, relatively high operating temperatures may increase the rate of light output degradation experienced by LEDs, which may shorten the useful life span of an LED and/or decrease the light output of the LED at a given point in time during the life span. Accordingly, it is important to draw heat away from LEDs to reduce the rate of light output degradation experienced thereby, such as by using a heat sink, fan, and/or the like. One particular area where operating temperatures need to be controlled to prevent adversely affecting the performance of an LED is a junction within the LED. Specifically, LEDs typically include p-type and n-type semiconductors joined together at a junction. Relatively high temperatures generated at the junction of the LED may be especially problematic with respect to increasing the rate of light output degradation experienced by the LED.
Accordingly, there is a need for monitoring the operating temperature of an LED to determine if enough heat is being drawn away from the LED to prevent an increased rate of light output degradation. For example, there is a need for monitoring the operating temperature at a junction of p-type and n-type semiconductors within an LED.